Several patents teach methods of charge direction for liquid electrophotographic toners. In general, liquid toners are attractive because they satisfy the need for smaller toner particles than dry powder electrophotographic methods can deliver. These liquid-dispersed particles, however, need to have charge more or less permanently attached to them or they will not be impelled to move across the development gap of the print engine to form the image desired.
Charging schemes for liquid electrophotography (LEP) have previously taken one of the following forms: